KR20110090838A - Methods to prepare silicon-containing films - Google Patents

Abstract

PURPOSE: A method of manufacturing a silicon bearing film is provided to form a dielectric film comprising Si, Oxide, N, C, H and B. CONSTITUTION: A method of manufacturing a silicon bearing film is as follows. A substrate is put into an ALD reactor. Silicon precursor, comprising one or more selected from a group of precursors, is introduced into the ALD reactor. The ALD reactor is purged with gas. An oxygen source is introduced into the ALD reactor and then the ALD reactor is purged with gas. Previous steps are repeated until a desired thickness of a dielectric film is obtained. The dielectric film comprises nitrogen less than about 30 atomic weight% if being measured by photoelectron spectroscopy.

Description

METHODS TO PREPARE SILICON-CONTAINING FILMS

 Cross Reference to Related Application

This patent application claims priority to US Provisional Patent Application Serial No. 61 / 301,375, filed February 4, 2010.

Background of the Invention

DETAILED DESCRIPTION The present invention relates to methods and compositions for making silicon containing materials or membranes for use in various electronic applications, such as, but not limited to, stoichiometric or non stoichiometric silicon oxide, silicon oxynitride or silicon oxycarbonitride films. will be.

Thin films of silicon oxide are commonly used as dielectrics in semiconductor manufacturing because of their dielectric properties. In the fabrication of silicon-based semiconductor devices, silicon oxide films may be used as gate insulation, diffusion masks, sidewall spacers, hard masks, and anti-reflection coatings. ), As passivation and encapsulation, and for a variety of other purposes. In addition, silicon oxide films are becoming increasingly important for passivation of other composite semiconductor devices.

In addition to silica and oxygen, other elements may be present in the silicon dioxide film. Such other elements may sometimes be intentionally added into the constituent mixture and / or deposition process depending on the resulting application of the film or the desired final properties. For example, a nitrogen (N) element can be added to the silicon oxide film to form a silicon oxynitride film that can provide specific dielectric performance, such as a low leakage current. A germanium (G) element may be added to the silicon oxide film to provide a Ge doped silicon oxide that can reduce the deposition temperature of the film. Other elements, such as boron (B) or carbon (C), may be added to the silicon oxide film to increase etch resistance. However, depending on the application, certain elements may be undesirable even when present at low concentration levels in the film.

 For example, when a silicon dioxide film is used as an etch stop or simply a dielectric layer under an ultraviolet (DUV) photoresist, a small amount of nitrogen present in the film may interact with the DUV photoresist and the photoresist It can chemically amplify the material properties of the material or poison the photoresist and render some of the photoresist insoluble in the developer. As a result, residual photoresist may remain on the patterned feature edges or sidewalls of the structure. This can be detrimental to the photolithographic patterning process of semiconductor devices.

Another example of a silicon oxide film that does not contain nitrogen can be found in antireflective coating (ARC) applications. ARC provides accurate pattern replication in layers of energy sensitive resist by suppressing reflections from underlying material layers during resist imaging. However, conventional ARC materials contain nitrogen, examples of which are silicon nitride and titanium nitride. The presence of nitrogen in the ARC layer can chemically change the composition of the photoresist material. The chemical reaction between nitrogen and the photoresist material may be referred to as "photoresist poisoning." The photoresist poisoned material applied in typical patterning steps can cause features to be incorrectly formed in the photoresist or excessive residual photoresist after patterning, both of which adversely affect the PR process, such as the etching process. Can have For example, nitrogen can neutralize acids near the photoresist and ARC interfaces and cause residue formation, known as footing, which is curved or circular rather than the desired right angle at the interface of the bottom and sidewalls of the feature. It can also result in shape.

For some applications, plasma enhanced chemical vapor deposition ("PECVD") processes are used to produce silicon oxide films at lower deposition temperatures than typical thermochemical vapor deposition ("CVD") processes. Tetraethyloxysilane (“TEOS”) with the molecular formula Si (OC ₂ H ₅ ) ₄ is one or more oxygen source, eg, non-limiting, for PECVD deposition of silicon oxide films exhibiting minimal residual carbon contamination. As a common precursor that can be used with O ₂ or O ₃ . TEOS is supplied as a stable, inert, high vapor pressure liquid and is less dangerous than other silicon containing precursors such as SiH ₄ .

There is a general tendency to move to low deposition temperatures (eg, below 400 ° C.) for one or more of the following reasons: cost (eg, cheaper substrates can be used) and thermal budget (Eg due to the integration of temperature sensitive high performance films). In addition, for PECVD TEOS films, the gap fill and conformality may be relatively good at low temperatures. However, the film quality of a PECVD TEOS film may be poorer because the film does not have a stoichiometric composition, is rich in hydrogen, and / or has a low film density and / or exhibits a fast etch rate. As such, alternative precursors with better performance than TEOS are needed.

A brief overview of the invention

The present invention does not contain important elements such as nitrogen, carbon, halogens and hydrogen, or when measured by X-ray photoelectron spectroscopy (XPS), about 0 to about 30 atomic weight percent nitrogen and / or about 0 to about 30 atomic weight Provided are a method of forming a material or film comprising silicon and oxygen, comprising percent carbon and exhibiting a non-uniformity% of 5% or less. The non-uniformity% can be measured using the following standard equation: non-uniformity% = ((max-min) / (2 * average)). Films deposited using the methods and precursors described herein are very uniform in certain cases without having to resort to the aid of temperature, plasma, plasma-like methods, or a combination thereof. The present invention also provides a method of forming a dielectric film or coating on an article to be treated, such as a semiconductor wafer, that is substantially free of nitrogen and / or carbon or that contains relatively small amounts of nitrogen and carbon.

In other embodiments, the methods and precursors described herein can provide a material with a relatively low nitrogen content, which provides a controlled composition to the nitrogen doped oxide material. In other embodiments, the methods and precursors described herein can provide a material with a relatively low carbon content, which provides a controlled composition to the carbon doped oxide material. In such embodiments, the material may comprise about 0 to about 30 atomic weight percent nitrogen and / or carbon as measured by XPS. In certain embodiments, the precursors used can produce very high purity SiO ₂ materials, where other materials, including carbon, nitrogen, chlorine and halogens, and other species that can be quantified by XPS Elements are present in undetectable amounts.

In one aspect, the invention provides a method of forming a film comprising silicon and oxygen on one or more surfaces of a substrate, the method comprising:

Providing one or more surfaces of the substrate in a reaction chamber,

By a deposition process selected from a chemical vapor deposition process and an atomic layer deposition (ALD) process using a silicon precursor and optionally an oxygen source comprising at least one precursor selected from the group of precursors having formulas (I), (II) and (III) Forming said film on at least one surface, said dielectric film comprising less than about 5 atomic percent nitrogen or carbon as measured by XPS:

Wherein R, R ¹ and R ² are each independently an alkyl group, an aryl group, an acyl group or a combination thereof. In embodiments where the membrane comprises nitrogen or carbon, a nitrogen source and / or a carbon source may also be introduced during the film formation step. In such embodiments, exemplary nitrogen sources, including but not limited to NH ₃ , N ₂ O, NH ₂ (CH ₃ ), and combinations thereof, may be introduced during the film formation step and / or further introduction steps. have. The carbon source and the nitrogen source may be the same.

In another aspect, the invention provides a method of forming a film comprising silicon and oxygen by an atomic layer deposition (ALD) process, which method comprises:

a. Placing the substrate in an ALD reactor;

b. Introducing a silicon precursor comprising at least one precursor selected from the group of precursors having formulas (I), (II) and (III) and optionally an oxygen source into the reactor, wherein R, R ¹ and Each R ² is independently an alkyl group, an aryl group, an acyl group or a combination thereof:

;

;

c. Purging the ALD reactor with a gas;

d. Introducing an oxygen source into the ALD reactor;

e. Purging the ALD reactor with a gas; And

f. Repeating steps b to d until the film of the desired thickness is obtained, wherein the dielectric film comprises less than about 5 atomic% carbon and / or nitrogen as measured by XPS.

In another aspect, the invention provides a method of forming a film comprising silicon oxide on one or more surfaces of a substrate using an ALD or CVD process, which method comprises:

a. Placing the substrate into the reactor;

b. A silicon precursor comprising at least one precursor selected from the group of precursors having Formulas I, II and III and optionally introducing an oxygen source into the reactor to deposit the film on the at least one surface, wherein the dielectric The membrane comprises from about 0 atomic weight percent to about 30 atomic weight percent carbon and / or nitrogen as measured by XPS.

Detailed description of the invention

The present invention provides a method of forming a very uniform dielectric film (e.g., such a film shows a% non-uniformity of 5% or less as measured using the following standard equation:% non-uniformity = ( Max-min) / (2 * average)). Dielectric films produced using the methods described herein generally contain mainly silicon and oxygen. In certain embodiments, the dielectric film is substantially free of any other element, such as nitrogen, carbon, chlorine and halogen, and hydrogen. As used herein, the term "substantially free" means a membrane comprising 2 atomic weight percent or less nitrogen as measured by XPS. In other embodiments, the dielectric film may contain other elements, such as nitrogen and / or carbon, in amounts ranging from about 2 atomic% to about 30 atomic%, and may contain other elements depending on the process conditions or additives used in the process. Can be. In certain embodiments, the methods described herein do not require plasma assist and / or are performed at low temperatures (eg, 600 ° C. or less). In another embodiment, the methods described herein are performed using a low temperature (eg, 450 ° C. or less) thermal process. The membranes described herein are dielectric membranes, meaning that such membranes exhibit dielectric constants that are typically 7 or less, 6 or less, or 5 or less. In certain embodiments, the resulting material may also contain elements such as boron, aluminum, and / or other elements that may contribute to the desired characteristics of the material. These elements may be introduced into the process as elements of separate additives or as substituents of the main precursor.

The method used to form the dielectric film or coating is a deposition process. Examples of suitable deposition processes for the methods described herein include, but are not limited to, cyclic CVD (CCVD), metal organic CVD (MOCVD), thermal chemical vapor deposition, plasma enhanced chemical vapor deposition. vapor deposition (PECVD), high density PECVD, photon assisted CVD, plasma-photon assisted CVD (PPECVD), cryogenic chemical vapor deposition, chemical assisted vapor deposition ), Hot-filament chemical vapor deposition, CVD of liquid polymer precursors, deposition from supercritical fluids, and low energy CVD (LECVD). In certain embodiments, the metal containing film is deposited by a plasma enhanced ALD (PEALD) or plasma enhanced cyclic CVD (PECCVD) process. As used herein, the term “chemical vapor deposition process” refers to any process in which a substrate is exposed to one or more volatile precursors, where the precursor reacts and / or decomposes on the substrate surface to produce the desired deposit. As used herein, the term “atomic layer deposition process” refers to self-limiting (eg, deposition in each reaction cycle), which deposits a conformal film or material onto a substrate of varying composition. Sequential surface chemistry). Although precursors, reagents and sources used in the present invention may sometimes be described as "gaseous", the precursors may be combined with an inert gas or by direct vaporization, bubbling or sublimation, or It is understood that it can be a liquid or a solid carried into the reactor without an inert gas. In some cases, the vaporized precursor may pass through a plasma generator. In one embodiment, the dielectric film is deposited using an ALD process. In another embodiment, the dielectric film is deposited using a CCVD process. In further embodiments, the dielectric film is deposited using a thermal CVD process. In another embodiment, the precursor can be condensed onto the substrate with minimal reaction and then post-treatment to assist in bringing the material to a solid state and adhering to the article to be deposited. There are a number of methods that allow the use of process conditions to form a film from chemical precursors, but the final properties of the deposited material may be uniquely determined by the nature of the chemical precursor or the additive used with such precursor. It can be recognized that there is.

In certain embodiments, the method described herein prevents pre-reaction of precursors by using an ALD or CCVD method that separates precursors prior to introduction into and / or during introduction into the reactor. In this regard, deposition techniques such as ALD or CCVD processes are used to deposit the dielectric film. In one embodiment, the film is deposited by an ALD process by alternatively exposing the substrate surface to one or more silicon containing precursors, oxygen sources, or other precursors or reagents. Film growth proceeds by surface reaction, pulse length of each precursor or reagent, and self-limiting control of the deposition temperature. However, when the surface of the substrate is saturated, film growth stops.

In certain embodiments, the precursor is introduced neat or without additional reactants or additives to condense, fill a feature or planarize the surface, and then undergo a reactant step, which reacts with the precursor. React or form a solid. In certain embodiments, this process changes the precursor and any additives using an oxidation process, a catalyst, or other form of energy (chemical, heat, radiation, plasma, photon, or any other ionized or non-ionized radiant energy). To form a solid material.

In order to form a dielectric film containing silicon and oxygen, which is substantially free of nitrogen, it is preferred that the silicon-containing precursor does not contain nitrogen. In certain embodiments it is also preferred that the precursor is sufficiently reactive to deposit the film at a relatively low temperature (eg, 400 ° C. or less). Despite the desire for precursor reactivity, the precursor must also be stable enough to not decompose or change to any significant extent over time (eg, an annual rate of change of less than 1%). In addition, in these or other embodiments, it is preferred that the deposition method be performed without a plasma. Without wishing to be bound by theory, it is believed that the reactivity to oxidize substituted silanes is proportional to the number of hydrogen atoms bonded to the silicon atoms.

The methods described herein include silicon containing precursors selected from silicon precursors including one or more precursors selected from the group of precursors having Formulas I, II, and III; Optionally a further silicon containing precursor, optionally an oxygen source or oxygen reagent, and optionally a reducing agent are used to form the dielectric film:

Wherein R, R ¹ and R ² are each independently an alkyl group, an aryl group, an acyl group or a combination thereof. The choice of precursor material for deposition depends on the resulting dielectric material or film desired. For example, the precursor material may be selected for the content of its chemical elements, the stoichiometric ratio of its chemical elements, and / or the resulting dielectric film or coating formed under CVD. In addition, the precursor material may be selected for a variety of other properties such as cost, stability, non-toxicity, handling properties, ability to maintain a liquid phase at room temperature, volatility, molecular weight, or combinations thereof.

In one embodiment of the methods described herein, the dielectric film is formed using a silicon precursor comprising one or more precursors selected from the group of precursors having Formulas I, II, and III:

Wherein R, R ¹ and R ² are each independently an alkyl group, an aryl group, an acyl group or a combination thereof. In Formulas I-III and throughout this specification, the term "alkyl" means a linear, branched or cyclic functional group having 1 to 20, or 1 to 12 or 1 to 6 carbon atoms. do. Exemplary alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, secondary-butyl, tert-butyl, pentyl, hexyl, octyl, decyl, dodecyl, tetradecyl, octadecyl, iso Pentyl, and tert-pentyl. In Formulas I through III and throughout this specification, the term "aryl" refers to a cyclic functional group having 6 to 12 carbon atoms. Exemplary alkyl groups include, but are not limited to, phenyl, benzyl, tolyl, and o-xylyl.

In certain embodiments, one or more of the alkyl groups, aryl groups and / or acyl groups may be substituted or unsubstituted or may have one or more atoms or groups of atoms substituted in place of hydrogen atoms. Exemplary substituents include, but are not limited to, oxygen, sulfur, halogen atoms (eg, F, Cl, I, or Br), nitrogen, boron, and phosphorus. In certain embodiments, silicon containing precursors having Formulas (I) through (III) may have one or more substituents that include an oxygen atom. In such embodiments, the need for an oxygen source during the deposition process can be eliminated. In other embodiments, silicon containing precursors having Formulas (I) through (III) have one or more substituents that include oxygen atoms and also use an oxygen source.

In certain embodiments, one or more of the alkyl group, aryl group, and / or acyl group may or may not be saturated. In embodiments where one or more alkyl or aryl groups are unsaturated, such groups contain one or more double bonds or triple bonds.

Examples of silicon-containing precursors having Formula I include tert-butoxysilane, isopropoxysilane, ethoxysilane, n-butoxysilane, isobutoxysilane, methoxysilane, or phenoxysilane. Examples of silicon-containing precursors having Formula II include di-tert-butoxysilane, diiso-propoxysilane, diethoxysilane, di-n-butoxysilane, diisobutoxysilane, dimethoxysilane, or diphenoxy There is a sisilane. Examples of silicon-containing precursors having Formula III include tri-tert-butoxysilane, triiso-propoxysilane, triethoxysilane, tri-n-butoxysilane, triiso-butoxysilane, trimethoxysilane Or triphenoxysilane. In one embodiment of the methods described herein, the silicon containing precursor comprises at least one of the following precursors:

In one specific embodiment, the silicon containing precursor comprises di-tert-butoxysilane.

In certain embodiments, the methods described herein further comprise one or more additional silicon containing precursors that are not silicon containing precursors having Formulas I-III described above. Examples of further silicon containing precursors include, but are not limited to, organo-silicon compounds, such as siloxanes (eg, hexamethyl disiloxane (HMDSO) and dimethyl siloxane (DMSO)); Organosilanes (eg, methylsilane; dimethylsilane; vinyl trimethylsilane; trimethylsilane; tetramethylsilane; ethylsilane; disilylmethane; 2,4-disilapentane; 1,2-disilanoethane; 2, 5-disilahexane; 2,2-disylylpropane; 1,3,5-trisilacyclohexane, and fluorinated derivatives of these compounds; phenyl containing organosilicon compounds (e.g., dimethylphenylsilane and diphenyl Methylsilane); oxygen-containing organosilicon compounds such as dimethyldimethoxysilane; 1,3,5,7-tetramethylcyclotetrasiloxane; 1,1,3,3-tetramethyldisiloxane; 1,3,5 , 7-tetrasila-4-oxo-heptane; 2,4,6,8-tetrasila-3,7-dioxo-nonane; 2,2-dimethyl-2,4,6,8-tetrasila-3 , 7-dioxo-nonane; octamethylcyclotetrasiloxane; [1,3,5,7,9] -pentamethylcyclopentasiloxane; 1,3,5,7-tetrasila-2,6-dioxo- Cyclooctane; hexamethylcyclotrisiloxane; 1,3-dimethyldisiloxane; 1,3,5,7,9-pentamethyl Clopentasiloxane, hexamethoxydisiloxane, and fluorinated derivatives of these compounds, and nitrogen-containing organosilicon compounds (eg, hexamethyldisilazane; divinyltetramethyldisilazane; hexamethylcyclotrisilazane; Dimethylbis (N-methylacetamido) silane; dimethylbis- (N-ethylacetamido) silane; bis (tert-butylamino) silane (BTBAS), bis (tert-butylamino) methylsilane (BTBMS ), Bis (N-methylacetamido) methylvinylsilane; bis (N-butylacetamido) methylvinylsilane; tris (N-phenylacetamido) methylsilane; tris (N-ethylacetamido) vinyl Silane; tetrakis (N-methylacetamido) silane; bis (diethylamineoxy) diphenylsilane; tris (diethylamineoxy) methylsilane; and bis (trimethylsilyl) carbodiimide).

In certain embodiments, the silicon containing precursor comprises a nitrogen containing organosilicon precursor with one or more NH fragments and one or more Si-H fragments. Suitable precursors containing both NH and Si-H fragments include, for example, bis (tert-butylamino) silane (BTBAS), tris (tert-butylamino) silane, bis (iso-propylamino) silane, Tris (iso-propylamino) silane, and mixtures thereof. In one embodiment, the precursor has the formula ( ^R5 NH) _n Si ^R6 _{mH4- (n + m)} , wherein R5 and R6 are the same or different and are alkyl, vinyl, allyl, phenyl, cyclic alkyl, fluoro Independently selected from the group consisting of alkyl, and silylalkyl, n is a number from 1 to 3, m is a number from 0 to 2, and the sum of “n + m” is 3 or less. In another embodiment, the silicon containing precursor comprises hydrazinosilanes having the formula (R ⁷ ₂ N-NH) _x SiR ⁸ _y H _{4- (x + y)} , wherein R ⁷ and R ⁸ are the same or different And independently selected from the group consisting of alkyl, vinyl, allyl, phenyl, cyclic alkyl, fluoroalkyl, silylalkyl, x is a number from 1 to 2, y is a number from 0 to 2, and “x + y The sum of "is a number of 3 or less. Examples of suitable hydrazinosilane precursors include, but are not limited to, bis (1,1-dimethylhydrazino) silane, tris (1,1-dimethylhydrazino) silane, bis (1,1-dimethylhydrazino) ethylsilane, bis ( 1,1-dimethylhydrazino) isopropylsilane, bis (1,1-dimethylhydrazino) vinylsilane, and mixtures thereof. In certain embodiments, the precursor or additive further comprises halogenated silanes, boranes, borazines, borates, and variants thereof.

Depending on the deposition method, for certain embodiments, one or more silicon containing precursors may be introduced into the reactor at a predetermined molar volume or from about 0.1 to about 1000 micromoles. In these or other embodiments, the silicon containing precursor may be introduced into the reactor for a predetermined time or from about 0.001 to about 500 seconds.

As mentioned above, a portion of the dielectric film deposited using the methods described herein may be formed in the presence of oxygen using an oxygen source, an oxygen reagent or a precursor comprising oxygen. The oxygen source may be introduced into the reactor in the form of one or more oxygen sources and / or additionally present in other precursors used in the deposition process. Suitable oxygen source gases include, for example, water (H ₂ O) (eg, deionized water, purified water, and / or distilled water), oxygen (O ₂ ), oxygen plasma, ozone (O ₃ ), NO, NO ₂ , Carbon monoxide (CO), carbon dioxide (CO ₂ ), and combinations thereof. In certain embodiments, the oxygen source typically comprises an oxygen source gas introduced into the reactor at a flow rate in the range of about 1 to about 2000 standard cubic centimeters (sccm), the flow rate range being a reaction process, desired. Depending on the material, substrate size, deposition rate, and the like. The oxygen source may be introduced prior to precursor introduction, simultaneously with the precursor, sequentially with the precursor in a repetitive cycle manner, or after all precursors have been introduced. In one particular embodiment, the oxygen source comprises water. For embodiments in which the film is deposited by an ALD or cyclic CVD process, the precursor pulse may have a pulse duration longer than 0.01, the oxygen source may have a pulse duration longer than 0.01 seconds, and the water pulse duration is 0.01 seconds. It can have a longer pulse duration. In another embodiment, the purge duration between pulses can be as short as 0.01 seconds or pulses occur continuously without an intermediate purge.

The deposition methods described herein can include one or more purge gases. The purge gas used to purge unconsumed reactants and / or reaction by-products is an inert gas that does not react with the precursor in certain embodiments. Exemplary inert gases include, but are not limited to, Ar, N ₂ , He, Xe, neon, H _2, and mixtures thereof. In certain embodiments, a purge gas such as Ar is fed into the reactor at a flow rate in the range of about 10 to about 2000 sccm for about 0.1 to 1000 seconds to purge unreacted material and any by-products that may remain in the reactor. .

In certain embodiments, for example, in embodiments where the dielectric constant further comprises components of nitrogen and / or carbon and / or other species, additional gases such as nitrogen source gas may be introduced into the reactor. Examples of additives may include, for example, NO, NO ₂ , ammonia, ammonia plasma, hydrazine, monoalkylhydrazines, dialkylhydrazines, hydrocarbons, heteroatomic hydrocarbons, boranes, borates, borazines, and combinations thereof. Can be.

In certain embodiments of the methods described herein, the temperature of the reactor or deposition chamber may range from ambient temperature (eg, 25 ° C.) to about 700 ° C. Exemplary reactor temperatures for ALD or CVD deposition include ranges having any one or more of the following endpoints: 25, 50, 75, 100, 125, 150, 175, 200, 225, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, or 700 ° C. Examples of specific reactor temperature ranges include, but are not limited to, 25 ° C. to 375 ° C., or 75 ° C. to 700 ° C., or 325 ° C. to 675 ° C. In these or other embodiments, the pressure may range from about 0.1 Torr to about 100 Torr or from about 0.1 Torr to about 5 Torr. In one specific embodiment, the dielectric film is deposited using a thermal CVD process in a pressure range of 100 mTorr to 600 mTorr. In another particular embodiment, the dielectric film is deposited using an ALD process at a pressure range of 1 Torr or less.

In certain embodiments of the methods described herein, the temperature of the substrate in the reactor or deposition chamber may range from ambient temperature (eg, 25 ° C.) to about 700 ° C. Exemplary substrate temperatures for ALD or CVD deposition include ranges having any one or more of the following endpoints: 25, 50, 75, 100, 125, 150, 175, 200, 225, 250, 275, 300, 325, 350 , 375, 400, 425, 450, 475, 500, 525, 550, 575, 600, 625, 650, 675, or 700 ° C. Examples of specific substrate temperature ranges include, but are not limited to, 25 ° C. to 375 ° C., or 75 ° C. to 700 ° C., or 325 ° C. to 675 ° C. In certain embodiments, the substrate temperature may be the same or in the same temperature range as the reactor temperature during deposition. In other embodiments, the substrate temperature is different from the reactor temperature during deposition.

Each step of supplying precursors, oxygen sources, and / or other precursors, source gases, and / or reagents may be performed to change the stoichiometric composition of the final dielectric film by varying the time of supplying them.

Energy is applied to one or more precursors, oxygen sources, reducing agents, other precursors or combinations thereof to induce a reaction, to form a dielectric film or to coat a substrate. Such energy may be supplied by thermal, plasma, pulsed plasma, helicon plasma, high density plasma, inductively coupled plasma, X-rays, e-beams, photons, and remote plasma methods, but It is not limited to. In certain embodiments, secondary RF frequency sources can be used to adjust plasma characteristics at the substrate surface. In embodiments where the deposition comprises plasma, the plasma-generating process may be a direct plasma-generating process in which the plasma is generated directly in the reactor, or alternatively a remote where plasma is generated outside of the reactor and fed into the reactor. Plasma-generating processes.

Silicon-containing precursors and / or other precursors may be delivered to reaction chambers such as CVD or ALD reactors in a variety of ways. In one embodiment, a liquid delivery system can be used. In an alternative embodiment, a unit, such as a liquid delivery and flash vaporization process, is used that allows for delivery of low volatility materials in volume, using a turbo vaporizer manufactured by MSP Corporation (Shoreview, MN), Induce reproducible transfer and deposition without thermal degradation. In liquid delivery formulations, the precursors described herein can be delivered in pure liquid form or alternatively can be used in solvent formulations or compositions containing the same. Thus, in certain embodiments the precursor formulation may comprise solvent component (s) of suitable properties that may be desirable and advantageous to certain end applications for forming a film on a substrate.

In one embodiment of the methods described herein, cyclic deposition processes such as CCVD, ALD, or PEALD can be used, wherein one or more silicon-containing precursors having Formulas I-III and combinations thereof and optionally oxygen sources such as , Ozone, oxygen plasma or water plasma is used. The gas line from the precursor canister to the reaction chamber is heated to one or more temperatures according to the process requirements and the vessel of silicon-containing precursors having formulas (I) to (III) is injected into a vaporizer maintained at one or more temperatures for direct liquid injection. Argon and / or other gas flows may be used as the carrier gas to assist in the delivery of one or more silicon-containing precursors to the reaction chamber during precursor pulsing. In certain embodiments, the reaction chamber process pressure is about 1 Torr or less. In a typical ALD or CCVD process, a substrate such as a silicon oxide substrate is first heated at a heater stage in a reaction chamber exposed to a silicon-containing precursor to form a complex and to be chemically adsorbed on the surface of the substrate. A purge gas such as argon purges excess complexes that are not adsorbed from the process chamber. After sufficient purging, an oxygen source can be introduced into the reaction chamber to react with the adsorbed surface and then the reaction by-products are removed from the chamber by another gas purge. The process cycle can be repeated to obtain the desired film thickness. In these or other embodiments, the steps of the methods described herein may be performed in a variety of orders, and may be performed sequentially or concurrently (eg, during at least some other steps), and these may be performed in any combination It may be. Each step of supplying the precursor and the oxygen source gas may be performed to change the stoichiometric composition of the final dielectric film by changing the period of time of supplying them.

In another embodiment of the methods described herein, the dielectric film is formed using an ALD deposition method comprising the following steps:

a. Introducing a silicon precursor comprising at least one selected from the group of precursors having Formulas I, II, and III and optionally an oxygen source, a nitrogen source, or a combination thereof and chemically adsorbing the one or more silicon precursors onto the substrate:

Wherein R, R ₁ , and R ₂ are each independently an alkyl group, an aryl, acyl group, or a combination thereof;

b. Purging away one or more silicon-containing precursors that did not react using a purge gas;

c. Optionally, introducing an oxygen source on the heated substrate and reacting with the adsorbed one or more silicon-containing precursors; And

d. Optionally, removing the unreacted oxygen source.

The steps described above form one cycle for the method described herein; The cycle can be repeated until a dielectric film of the desired thickness is obtained. In these or other embodiments, the steps of the methods described herein may be performed in a variety of orders, and may be performed sequentially or concurrently (eg, during at least some other steps), and these may be performed in any combination It may be. Each step of supplying the precursors and optionally the oxygen source gas may be performed to change the stoichiometric composition of the final dielectric film by changing the period of time of supplying them. For multi-component dielectric films, other precursors such as silicon-containing precursors, nitrogen-containing precursors, reducing agents, or other reagents may alternatively be introduced into the reactor chamber in step "a". In this embodiment, the reactor temperature may range from ambient temperature to 600 ° C. In these or other embodiments, the pressure of the reactor may be maintained at 1 Torr or less.

In further embodiments of the methods described herein, the dielectric film is deposited using a thermal CVD process. In this embodiment, the method comprises: wherein the reactor is maintained at a pressure range of 100 mTorr to 600 mTorr during the introduction step: in a reactor heated to an ambient temperature of about 700 ° C. or a temperature range of 400 to 700 ° C. Placing one or more substrates; And introducing into the reactor a silicon precursor comprising at least one selected from the group of precursors having Formulas (I), (II), and (III) below and optionally a source selected from an oxygen source, a nitrogen source, or a combination thereof Deposition of the film:

Wherein R, R ₁ , and R ₂ are each independently an alkyl group, an aryl, acyl group, or a combination thereof. In certain embodiments, the pressure in the CVD reactor may range from about 0.01T to about 1T. The flow rate of the reactant gas, such as O ₂ , may range from 5 sccm to 200 sccm. The flow rate of the one or more silicon-containing precursor vapors may range from 5 sccm to 200 sccm. The deposition temperature is the same as the reactor wall temperature. It may range from ambient temperature to about 700 ° C or from about 400 ° C to about 700 ° C. Deposition time is intended for the process to obtain a film having the desired thickness. Deposition rates include, but are not limited to, one or more processes including deposition temperature, flow rate of O ₂ , flow rate of carrier gas (He), liquid mass flow of silicon-containing precursor, temperature of vaporizer, and / or pressure of reactor It can depend on the parameters. The vaporizer temperature may range from 20 ° C. to 150 ° C. The deposition rate of the material can range from 0.1 nm to 1000 nm per minute. The rate can be adjusted by changing any of the following non-limiting parameters: deposition temperature, vaporization temperature, flow of the LFC, flow rate of the reactive additive and / or pressure in the CVD reactor, for example.

In still other embodiments, the method can be performed using a cyclic CVD process. In this embodiment, the same ALD reactor can be used for the cyclic CVD process. One difference between the cyclic CVD process and the ALD method described above for depositing a uniform film free of nitrogen is that the doses of silicon precursor and oxygen precursor can be much higher than the doses used for ALD, so the deposition rate is higher than that of ALD. It can be much bigger. Deposition temperatures can range from ambient temperature to about 700 ° C or 400 ° C to about 700 ° C.

In certain embodiments, the final dielectric film or coating is exposed in a post-deposition treatment such as, but not limited to, plasma treatment, chemical treatment, ultraviolet exposure, electron beam exposure, and / or other treatments that affect one or more properties of the film. Can be.

The dielectric film described herein has a dielectric constant of 7 or less. Preferably, the membrane has a dielectric constant of 6 or less, or 5 or less, or 4 or less.

As previously mentioned, the methods described herein can be used to deposit a dielectric film on at least a portion of a substrate. Examples of suitable substrates include, but are not limited to, silicon, SiO ₂ , Si ₃ N ₄ , organosilica glass (OSG), fluorinated silica glass (FSG), silicon carbide, hydrogenated silicon carbide, silicon nitride, hydrogenation Silicon nitride, silicon carbonitride, hydrogenated silicon carbonitride, boronitride, antireflective coatings, photoresists, organic polymers, porous organic and inorganic materials, metals such as copper and aluminum, and diffusion barrier layers such as But not including TiN, Ti (C) N, TaN, Ta (C) N, Ta, W, or WN. The film is suitable for a variety of subsequent process steps such as chemical mechanical planarization (CMP) and anisotropic etching processes. The substrate may be uniform or patterned, smooth or feature, flat or non-flat.

Deposited dielectric films include, but are not limited to, computer chips, optical devices, magnetic information storage devices, coatings on support materials or substrates, microelectromechanical systems (MEMS), nanoelectromechanical systems, thin film transistors (TFTs), and Has an application that includes a liquid crystal display (LCD).

Brief description of several views in the drawing
FIG. 1 provides the results of X-ray photoelectron spectroscopy (XPS) for films deposited using the method described in Example 1. FIG.
FIG. 2 provides thickness uniformity for three exemplary films deposited using t-butyl silane, diethylsilane, and di-tert-butoxysilane (DTBOS) according to the method described in Example 2. FIG.
3 provides a plot of the dielectric constant obtained from an exemplary film deposited using one of the process conditions provided in Table 1 and deposited using the precursor DTBOS described above.
FIG. 4 is a comparison of the wet etch rate (WER) of films deposited using three different deposition temperatures or the BL1 conditions described in the examples at 400 ° C., 300 ° C., and 200 ° C. FIG. 4 shows that the DTBOS deposited film has a lower WER than the TEOS film at all temperatures.
5 provides a leakage current versus electric field plot for TEOS vs. DTBOS at 200 ° C. and 300 ° C. deposition for the BL1 conditions described in Table 3 of Example 4. FIG.
6 provides a leakage current versus electric field plot for TEOS vs. DTBOS at 200 ° C. and 300 ° C. deposition for the BL2 conditions described in Table 3 of Example 4. FIG.
FIG. 7 provides a plot of leakage current versus electric field for TEOS vs. DTBOS at 200 ° C. and 300 ° C. deposition for the BL3 conditions described in Table 3 of Example 4. FIG.
FIG. 8 is a comparison of dynamic secondary ion mass spectrometry data (D-SIMS) of DTBOS and bis (tertbutyl) aminosilane (BTBAS) in CVD films deposited from these precursors.

The following examples describe the dielectric film fabrication methods described herein but are not intended to be limited to these in any case.

Example

In the examples below, unless otherwise noted, properties were obtained from sample films deposited on medium resistance (8-12 Ωcm) single crystal silicon wafer substrates. In this study, CVD deposition was performed using low pressure chemical vapor deposition (LPCVD) furnaces or ATV PEO 612 furnaces. The precursors were delivered to the furnace using a steam draw and line temperature adjusted based on the vapor pressure on the precursor material. The atomic layer deposition apparatus used in this study is an R & D designed horizontal tube furnace with an attached environmental oven for heated precursor delivery. The system can perform deposition at room temperature to 700 ° C. All plasma based depositions were performed on an Applied Materials Precision 5000 system in a 200 mm DXZ chamber mounted in an Advanced Energy 2000 Radio Frequency (RF) generator using a TEOS process kit.

In the examples below, the thickness and optical properties such as refractive index of the dielectric film were performed using standard reflectometers or ellipsometry measurement systems, such as the Filmtec 2000SE ellipsometer, using known data fitting techniques.

Characterization of the chemical composition of the membrane was obtained using a Physical Electronics 5000 Versaprobe XPS Spectrometer equipped with a multi-channel plate detector (MCD) and an Al monochromatic X-ray source. XPS data was collected using Alk _α X-ray excitation (25 mA and 15 kV). Low-resolution survey spectra were collected at 117 eV pass energy, 50 millisecond dwell time, and 1.0 eV / step. High-resolution region spectra were collected at 23.5 eV pass energy, 50 msec residence time, 0.1 eV / step. The analysis area is 100 μm at a constant angle of 45 °. Quantitative elemental analysis was determined by measuring the peak region from the high-resolution region spectrum and applying a transfer-function with modified atomic sensitivity coefficients. PHI Summit software was used for data collection and CasaXPS software was used for data analysis. The etch rate was calibrated for 203 nm SiO ₂ / Si and about 120 mA / min.

The etch test is a 6: 1 buffered oxide etch (“BOE”) solution with a volume ratio of 6 parts 40% NH ₄ F in water and 1 part 49% HF solution in water to form a buffered oxide etch. Was performed in. The exemplary dielectric film was placed in HF solution for 30 seconds, then washed and dried in deionized (DI) water before measuring for loss of material during etching. The process is repeated until the film is completely etched. The etch rate is later calculated from the slope of etch time versus etched thickness. With the silicon oxide films being compared, the films were measured at three different points across the film surface before and after etching.

Fourier Transform Infrared Spectroscopy (FTIR) data was collected on a wafer using a Thermo Nicolet nexus 470 system or similar system equipped with a DTGS KBR detector and a KBr beam splitter. Background spectra were collected on similar medium resistive wafers to remove CO ₂ and water from the spectra. Data is generally obtained in the region of 4000 to 400 cm ⁻¹ by collecting 32 scans with a resolution of 4 cm ⁻¹ . All films were commonly baseline modified, the intensity was normalized to a film thickness of 500 nm, and the peak area and height of interest were measured.

The dielectric constant of each sample membrane was measured according to ASTM standard D150-98. The dielectric constant, k, was calculated from the C-V curve measured using, for example, the MDC 802B-150 Mercury Probe. It consists of a probe stage that makes electrical contact in the film to hold and measure a sample, a Keithley 236 source meter for C-V measurements, and an HP4284A LCR meter. Si wafers with relatively low electrical resistance (sheet resistance less than 0.02 ohm-cm) are used to deposit films for C-V measurements. Front contact mode is used to form electrical contacts in the film. Liquid metal (mercury) is pushed through the thin tube from the reservoir to the surface of the wafer to form two electrically conductive contacts. The contact area is calculated based on the diameter of the tube from which mercury is pushed out. The dielectric constant is then calculated from the formula k = capacitance × contact area / film thickness.

Example 1 Deposition of Silicon Oxide Films by Chemical Vapor Deposition Using Di-tert-Butoxysilane (DTBOS)

An exemplary silicon oxide film is deposited using precursor DTBOS and oxygen as the oxygen source. The deposition conditions of each film are shown in Table 1. The properties of each membrane are shown in Table 2.

TABLE 1

sccm = standard cm ³ per minute

Table 2

A typical XPS of any of the exemplary membranes from Example 1, which are highly uniform and free of elements, such as carbon and nitrogen, is shown in FIG. 1 and the composition of the different elements is also shown in Table 3. As can be seen in both FIG. 1 and Table 3, neither carbon nor nitrogen was detected in the membrane.

Table 3. Chemical Composition (Atom%) of High Purity Silicon Dioxide Film

ND-amount below detection limit

Table 3B. Chemical composition (atomic%) of nitrogen-free silicon dioxide film corresponding to the spectrum shown in FIG.

Example 2: Thickness Uniformity of Membranes

The thickness of the nitrogen-free silicon dioxide film formed using the methods and compositions described herein was measured using an ellipsometer. In contrast to the low uniformity of nitrogen silicon dioxide films deposited using the methods currently used, films deposited using the methods described herein show a sharp improvement in film uniformity in the substrate (or wafer). A comparison of film thickness uniformity between a film using the invention and a film using existing methods is provided in FIG. 2 where the x axis represents the measurement position on the wafer substrate and the y axis represents the variation in thickness at each point from the average thickness of the film. . It can be seen from FIG. 2 that the film deposited using the method described herein is more uniform across the wafer substrate compared to other films.

The general formula used for thickness uniformity for thin films is, namely, uniformity = (maximum thickness min. Thickness) / (2 * average) * 100%.

The thickness uniformity of the films formed using the methods described herein is shown in Table 4. The results in Table 4 show that the film uniformity from the method described herein is at least 10 times better than the film formed using existing methods (precursors).

Table 4. Thickness uniformity (%) of various silicon dioxide films

Example 3: K and Dielectric Constant

The dielectric constant of the silicon oxide film formed using the method described herein is derived from the C-V plot shown in FIG. 3. It was found that the dielectric constant of the membrane, for the known membrane thickness and the contact area of the Mercury probe used, was 4.47.

Example 4 Comparison of Films Deposited by Plasma Enhanced CVD Using Di-tert-Butoxysilane Precursor and Tetraethoxysilane Under Different Process Conditions

In the examples below, unless otherwise stated, the properties were obtained from sample films deposited on medium resistance (8-12 Ωcm) single crystal silicon wafer substrates. Deposition temperatures were 200, 300, and 400 ° C.

Table 5 provides a summary of three different process conditions used to compare precursor or di-tert-butoxysilane (DTBOS) and comparative precursor tetraethoxysilane (TEOS). Three different process conditions are indicated as BL-1, BL-2 and BL-3.

Table 5

Table 6 provides a comparison of the K value, deposition rate and wet etch rate of TEOS versus DTBOS for BL1 conditions. The deposition rate of DTBOS is higher than TEOS for the same volume flow of precursor. This shows that DTBOS can be more efficient than TEOS for PECVD deposition. In addition, the WER of the DTBOS-deposited membrane is the same or better than that of the TEOS-deposited membrane. This means that the density of SiO ₂ films deposited using DTBOS precursors is the same or better.

Table 6

Table 7 provides a comparison of K values, deposition rates, and wet etch rates of TEOS versus DTBOS for BL2 process conditions. The deposition rate of DTBOS is higher than TEOS for the same volume flow of precursor. This demonstrates the high efficiency of DTBOS in PECVD deposition. However, WER is the same or better than that for TEOS membranes. This means that the density of SiO ₂ film formed from DTBOS is the same or superior.

TABLE 7

Table 8 provides a comparison of K values, deposition rates, and wet etch rates of TEOS vs. DTBOS for BL3 process conditions. The deposition rate of the DTBOS is the same as TEOS for the same volume flow of precursor. However, WER is clearly superior to that for TEOS membranes. This means that the density of SiO ₂ film formed from DTBOS is excellent. In addition, the K value for DTBOS is lower, which means lower moisture absorption.

Table 8

4 shows a comparison of the WER of a deposited film using all baseline conditions and deposition temperatures described in Table 3 (eg, BL-1, BL-2, and BL-3 and 200, 300, and 400 ° C.). Shows. DTBOS membranes have a lower WER for the same K, which means higher density and higher quality oxide membranes. Thus, DTBOS can produce films of better quality than TEOS at relatively low temperatures in PECVD deposition.

Table 9 below provides a breakdown voltage (Vbd) comparison of TEOS and DTBOS at different temperatures under the process conditions BL1, BL2 and BL3 defined in the previous Table 5. In general, the breakdown voltage is 8-12 MV / cm and can be compared between the two precursors. 5, 6, and 7 show leakage currents versus electric field plots for TEOS and DTBOS deposited films at 200 ° C. and 300 ° C. depositions.

FIG. 5 provides a plot of leakage current vs. electric field for TEOS vs. DTBOS at 200 ° C. and 300 ° C. deposition for BL1 conditions. Since the DTBOS has a higher K and WER at 200 ° C. than TEOS for BL1, the effect on membrane leakage is also observed. However, this is the only condition where DTBOS shows poor leakage performance than TEOS. As shown in the 300 ° C. data and FIGS. 6 and 7, the DTBOS SiO ₂ leakage is generally superior to TEOS SiO ₂ leakage.

FIG. 6 provides a leakage current versus electric field plot for TEOS vs. DTBOS at 200 ° C. and 300 ° C. deposition for BL2 conditions. Although DTBOS has higher D / R; The leakage of the DTBOS SiO ₂ film is lower than that for TEOS, which explains the excellent electrical properties and supports the WER data.

FIG. 7 provides a plot of leakage current versus electric field for TEOS vs. DTBOS at 200 ° C. and 300 ° C. deposition for BL3 conditions. Overall for BL3, leakage is lower in DTBOS than TEOS.

Table 9

8 provides dynamic secondary ion mass spectrometer data (D-SIMS) of DTBOS compared to bis (tertbutyl) aminosilane, (aka. BTBAS). From the XPS data for BTBAS, it can be seen that the CVD process generally provides ˜10 atomic% C (excluding hydrogen). This is compared with Table 3, where no carbon levels in the DTBOS membrane can be detected. The D-SIMS data indicates that the carbon content is about 10 ² (two orders of magnitude) times less, suggesting that the actual carbon levels of these films, deduced from comparison with the BTBAS XPS data, may be <0.1 atomic%.

ALD deposition data from DTBOS is shown in Table 10. The deposition of silicon oxide is explained by the proper refractive index for these films.

Table 10

The present invention also relates to tertiary butoxysilane, isopropoxysilane, ethoxysilane, n-butoxysilane, isobutoxysilane, methoxysilane, phenoxysilane, di-tert-butoxysilane, diiso-pro Foxysilane, diethoxysilane, di-n-butoxysilane, diisobutoxysilane, dimethoxysilane, diphenoxysilane, tri-tert-butoxysilane, triiso-propoxysilane, triethoxysilane, Electropolished with inlet and outlet with low-purity, low-purity valves containing tri-n-butoxysilane, triiso-butoxysilane, trimethoxysilane, or triphenoxysilane ) A package with a reactant as described above, comprising a stainless steel container.

The reactants and methods of the present invention consist of an optical device, a magnetic information storage device, a support material or a coating on a substrate, a microelectromechanical system (MEMS), a nanoelectromechanical system, a thin film transistor (TFT), and a liquid crystal display (LCD). It can be used to make a device selected from the group.

Claims (14)

A method of forming a dielectric film on one or more surfaces of a substrate, the method comprising:
Providing at least one surface of the substrate in a reaction chamber;
A method of forming a dielectric film on at least one surface of a substrate comprising introducing a silicon precursor comprising at least one precursor selected from the group of precursors having Formulas (I), (II) and (III) into the reaction chamber to form a dielectric film :

Wherein R, R ¹ and R ² are each independently an alkyl group, an aryl group, an acyl group or a combination thereof. The method of claim 1, wherein at least one source selected from an oxygen source, a nitrogen source, or a combination thereof is introduced into the reaction chamber. The process of claim 1, wherein the dielectric film is selected from cyclic chemical vapor deposition, plasma enhanced chemical vapor deposition, or atomic layer deposition. Formed by the method. The method of claim 1, wherein the silicon precursor comprises di-tert-butoxysilane. The method of claim 1, wherein the silicon precursor comprises di-tert-pentoxysilane. The method of claim 2, wherein the oxygen source comprises oxygen. The method of claim 2, wherein the oxygen source comprises ozone. A method of forming a dielectric film containing silicon and oxygen by an atomic layer deposition (ALD) process,
a. Placing the substrate in an ALD reactor;
b. Introducing a silicon precursor comprising at least one precursor selected from the group of precursors having Formulas (I), (II) and (III) into the ALD reactor, wherein R, R ₁ and R ₂ in Formulas (I), (II) and (III) Each independently an alkyl group, an aryl group, an acyl group or a combination thereof:

;
c. Purging the ALD reactor with a gas;
d. Introducing an oxygen source into the ALD reactor;
e. Purging the ALD reactor with a gas; And
f. Repeating steps b through d until a dielectric film of a desired thickness is obtained, said dielectric film comprising up to about 30 atomic weight percent nitrogen as measured by photoelectron spectroscopy (XPS) A method of forming a dielectric film comprising silicon and oxygen by a deposition process. The method of claim 1, wherein a nitrogen source is introduced into the reaction chamber. The method of claim 1, wherein a thermal CVD process is used and the dielectric film comprises up to about 30 atomic weight percent nitrogen as measured by XPS. The method of claim 10, wherein at least one source selected from an oxygen source, a nitrogen source, or a combination thereof is introduced into the reaction chamber. A film produced from the method of claim 1, wherein the composition is Si _a O _b N _c C _d H _e B _f , wherein a is 10-50 at%, b is 10-70 at%, c is 0-30 at%, d from 0 to 30 at%, e from 0 to 50 at%, and f from 0 to 30 at%. Tert-butoxysilane, isopropoxysilane, ethoxysilane, n-butoxysilane, isobutoxysilane, methoxysilane, phenoxysilane, di-tert-butoxysilane, diiso-propoxysilane, diethoxy Silane, di-n-butoxysilane, diisobutoxysilane, dimethoxysilane, diphenoxysilane, tri-tert-butoxysilane, triiso-propoxysilane, triethoxysilane, tri-n-part An electropolished stainless steel vessel having an inlet and an outlet having a low-density, high purity valve containing oxysilane, triiso-butoxysilane, trimethoxysilane, or triphenoxysilane. Optical devices, magnetic information storage, support material or coatings on substrates, microelectromechanical systems (MEMS), nanoelectromechanical systems, thin film transistors (TFTs), And a liquid crystal display (LCD). A device manufactured using the method of claim 1.

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